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• • iii iiiiiiiiniu iii 999 January 20, 2000 To: Chris Kamnikar,~C /ar~l Mount, Jim Stevens From: lames Dillie Re: Review of Adequacy Letter, Riverview Reservoir, M-99-098 Per Mr. Mount's request, I reviewed the technical aspects of Chris's adequacy letter to the operator of the referenced permit application. I offer the following suggestions/recommendations: A) In order to fully evaluate the stability of the various sideslopes, outslopes, embankments, etc. the applicant needs to provide an accurate lithologic profile of the soils; including wet and dry density, soil composition, internal friction angle, cohesion, phreatic surface, etc. The items are adequately addressed in pazagraphs 1, 2 and 3 of the adequacy letter. B) Paragraph 4 of the adequacy letter asks the applicant to include the weight of the conveyor systems to the loading of the embankments. If these are critical structures, the conveyor systems should be included in the stability analyses. Otherwise, it is not necessary to include the equipment since conveyor systems, normally, do not add much load over a large area. C) If the Fish Hatchery has lined ponds, lagoons or other contained holding facilities (concrete or metal containers) the water surface issue does not apply. So, I suggest you find out what kind of facilities exist at the Hatchery before requiring any further stability analyses from the applicant. If the ponds, lagoons and other facilities, which lie within 200 feet of the affected lands, are no[ lined structures, the effects of mining on their stability should be analyzed (see paragraph 5). D) Rather than making an out-and-out statement that a fence qualifies as a man-made structure, I believe you need to allow the applicant the opportunity to "provide [he Division with evidence that a structure is not included within the regulatory definition.", pursuant to Bruce's January 11, 2000 memo, prior to requiring compliance with Rule 6.4. l9 (see paragraph 6). E) Paragraph 7. Good question since the size of the house and/or the structural materials will make a difference in the amount of foundation loading. F) Since Adams County is located in a seismic zone with possible minor to moderate seismic intensity, I suggest using a 0.05 seismic coefficient in the slope stability analyses to determine an appropriate FOS for pseudo-static conditions (see paragraph 8). G) Paragraphs 9 thru 12 adequately address the related issues. H) It appeazs Tom addressed paragraphs 13 thrv 15.